Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other wor...Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other words,the PbI2 content in the precursor and as formed film will affect the efficiency and stability of the PSCs.With moderate residual PbI2,it passivates the bulk/surface defects of perovskite,reduces the interfacial recombination,promotes the perovskite stability,minimizes the device hysteresis,and so on.Deficient PbI2 residue will reduce the interfacial passivation effect and device performance.In addition to facilitating the non-radiative recombination,over PbI2 residue can also lead to electronic insulation in the grain boundary and deteriorate the device performance.However,the impact and regulation of PbI2 residue on the device performance and stability is still not fully understood.Herein,a comprehensive and detailed review is presented by discussing the PbI2 residue impact and its regulation strategies(i.e., elimination,facilitation and conversion of the residue PbI2) to manipulate the PbI2 content,distribution and forms.Finally,we also show future outlooks in this field,with an aim to help further the progression of high-efficiency and stable PSCs.展开更多
The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material.In particular,nanocrystals(NCs)of inorganic perovskites have demonstrated excellen...The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material.In particular,nanocrystals(NCs)of inorganic perovskites have demonstrated excellent performance for light-emitting and display applications.However,the presence of surface defects on the NCs negatively impacts their performance in devices.Herein,we report a compatible facial post-treatment of CsPbI_(3) nanocrystals using guanidinium iodide(GuI).It is found that the GuI treatment effectively passivated the halide vacancy defects on the surface of the NCs while offering effective surface protection and exciton confinement thanks to the beneficial contribution of iodide and guanidinium cation.As a consequence,the film of treated CsPbI_(3) nanocrystals exhibited significantly enhanced luminescence and charge transport properties,leading to high-performance light-emitting diode with maximum external quantum efficiency of 13.8%with high brightness(peak luminance of 7039 cd m^(−2) and a peak current density of 10.8 cd A^(−1)).The EQE is over threefold higher than performance of untreated device(EQE:3.8%).The operational half-lifetime of the treated devices also was significantly improved with T50 of 20 min(at current density of 25 mA cm^(−2)),outperforming the untreated devices(T50~6 min).展开更多
Perovskite solar cells have developed rapidly in the past decades.However,there are large amounts of ionic defects at the surface and grain boundaries of perovskte films which are detrimental to both the efficiency an...Perovskite solar cells have developed rapidly in the past decades.However,there are large amounts of ionic defects at the surface and grain boundaries of perovskte films which are detrimental to both the efficiency and stability of perovskite solar cells.Here,an organic halide salt pyridinium iodide(PyI) is used in cation-anion-mixed perovskite for surface defect passivation.Different from the treatment with Lewis base pyridine(Py) which can only bind to the under-coordinated Pb ions,zwitterion molecule PyI can not only fill negative charged iodine vacancies,but also interact with positive charged defects.Compared with Py treatment,PyI treatment results in smoother surface,less defect densities and nonradiative recombination in perovskite,leading to an improved VOC, negligible J-V hysteresis and stable performance of devices.As a result,the champion PyI-treated planar perovskite solar cell with a high VOC of 1.187 V achieves an efficiency of 21.42%,which is higher than 20.37% of Py-treated device,while the pristine device without any treatment gets an efficiency of 18.83% at the same experiment conditions.展开更多
Formamidinium lead triiodide(FAPbI_(3))is a research hotspot in perovskite photovoltaics due to its broad light absorption and proper thermal stability.However,quite a few researches focused on the stability of the FA...Formamidinium lead triiodide(FAPbI_(3))is a research hotspot in perovskite photovoltaics due to its broad light absorption and proper thermal stability.However,quite a few researches focused on the stability of the FAPbI_(3) perovskite precursor solutions.Besides,the most efficient FAPbI_(3) layers are prepared by the spin-coating method,which is limited to the size of the device.Herein,the stability of FAPbI_(3) perovskite solution with methylammonium chloride(MACl)or cesium chloride(CsCl)additive is studied for preparing perovskite film through an upscalable blade-coating method.Each additive works well for achieving a high-quality FAPbI_(3) film,resulting in efficient carbon electrode perovskite solar cells(pero-SCs)in the ambient condition.However,the perovskite solution with MACl additive shows poor aging stability that noα-FAPbI_(3) phase is observed when the solution is aged over one week.While the perovskite solution with CsCl additive shows promising aging stability that it still forms high-quality pureα-FAPbI_(3) perovskite film even the solution is aged over one month.During the solution aging process,the MACl could be decomposed into methylamine which will form some unfavored intermediated phase inducingδ-phase FAPbI_(3).Whereas,replacing MACl with CsCl could effectively solve this issue.Our founding shows that there is a great need to develop a non-MACl FAPbI_(3) perovskite precursor solution for cost-effective preparation of pero-SCs.展开更多
Study of two-dimensional(2D)magnetic materials is important for both fundamental research and application.Here we report molecular beam epitaxy growth of iodides,candidates for exhibiting 2D magnetism.Decomposition of...Study of two-dimensional(2D)magnetic materials is important for both fundamental research and application.Here we report molecular beam epitaxy growth of iodides,candidates for exhibiting 2D magnetism.Decomposition of CrI_(3)is utilized to produce stable gaseous I_(2)flux.Growth of MnI_(2),GdI_(3),and CrI_(2)down to monolayer is successful achieved by co-depositing I2 and corresponding metal atoms.The thin films of the three materials are characterized by scanning tunneling microscope and found to be insulators with bandgaps of 4.4 e V,0.6 e V,and 3.0 e V,respectively.The film growth paves the way for further study of magnetic properties at the 2 D limit.展开更多
The morphology of the copper iodide （CuI） film as an inorganic p-type material has an important influence on enhancing the performance of polymer solar cells （PSCs）. A self-assembled monolayer of 3-aminopropanoic ...The morphology of the copper iodide （CuI） film as an inorganic p-type material has an important influence on enhancing the performance of polymer solar cells （PSCs）. A self-assembled monolayer of 3-aminopropanoic acid （C3-SAM） was used on the surface of indium tin oxide （ITO） before depositing the CuI films. Consequently, a well-distributed and smooth CuI film was formed with pinhole free and complete surface coverage. The root mean square of the corresponding CuI film was reduced from 3.63 nm for ITO/CuI to 0.77 nm. As a result, the average power conversion efficiency （PCE） of PSCs with the device structure of ITO/C3-SAM/CuI/P3HT：PC61BM/ZnO/Al increased significantly from 2.55% （best 2.66%） to 3.04% （best 3.20%） after C3-SAM treatment. This work provides an effective strategy to control the morphology of CuI films through interracial modification and promotes its application in efficient PSCs.展开更多
Two-dimensional(2D)topological insulators present a special phase of matter manifesting unique electronic properties.Till now,many monolayer binary compounds of Sb element,mainly with a honeycomb lattice,have been rep...Two-dimensional(2D)topological insulators present a special phase of matter manifesting unique electronic properties.Till now,many monolayer binary compounds of Sb element,mainly with a honeycomb lattice,have been reported as 2D topological insulators.However,research of the topological insulating properties of the monolayer Sb compounds with square lattice is still lacking.Here,by means of the first-principles calculations,a monolayer SbI with square lattice is proposed to exhibit the tunable topological properties by applying strain.At different levels of the strain,the monolayer SbI shows two different structural phases:buckled square structure and buckled rectangular structure,exhibiting attracting topological properties.We find that in the buckled rectangular phase,when the strain is greater than 3.78%,the system experiences a topological phase transition from a nontrivial topological insulator to a trivial insulator,and the structure at the transition point actually is a Dirac semimetal possessing two type-ⅠDirac points.In addition,the system can achieve the maximum global energy gap of 72.5 meV in the topological insulator phase,implying its promising application at room temperature.This study extends the scope of 2D topological physics and provides a platform for exploring the low-dissipation quantum electronics devices.展开更多
Conversion of methanol(MeOH) to 2,2,3-trimethylbutane(triptane) over zinc iodide(ZnI_2)catalyst was investigated in a closed batch reactor.Optimum operating parameters were searched and catalyst deactivation and regen...Conversion of methanol(MeOH) to 2,2,3-trimethylbutane(triptane) over zinc iodide(ZnI_2)catalyst was investigated in a closed batch reactor.Optimum operating parameters were searched and catalyst deactivation and regeneration behaviors were discussed.The fresh,spent and regenerated catalysts were characterized by XRD,TG and XRF measurements to elucidate the related mechanism.The experimental results showed that the triptane yield reached up to 12.2% under the process conditions,including a reaction temperature of 200℃,an initial pressure of 0.35 MPa,a reaction time of 2 h,and a Me OH to ZnI_2 molar ratio of 2.The catalyst was gradually deactivated after several run cycles.A small amount of iodine was lost and a certain amount of ZnO was formed on the deactivated ZnI_2 catalyst.Deactivation of the catalyst could be attributed to the reduction of ZnI_2 amount,resulted from iodine loss and formation of Zn O.It was firstly pointed out from our work that the deactivated catalyst could be well regenerated by the hydrogen iodide(HI) and the tert-butanol compensation method,wherein the latter was added as an initiator into the reaction system.The activity recovery of the deactivated(spent) catalyst might be related to the reformation of ZnI_2 and acceleration of the initiation step of this reaction.展开更多
Previous reports of formamidinium/methylamine(FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example,through the inclusion of ...Previous reports of formamidinium/methylamine(FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example,through the inclusion of bromine and surface passivation.In this paper,we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase.Through low-temperature aging growth(LTAG)of a freshly deposited perovskite film,α-phase perovskites can be seeded in the intermediate phase and,at the same time,prevent beta-phase perovskite to nucleate.After postannealing,large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained,thereby eliminating the need of additional surface passivation step.Our pristine LTAG-treated solar cells could provide PCEs of greater than 22%without elaborate use of bromine or an additional passivation layer.More importantly,when using this LTAG process,the growth of the pure alpha-phase FAMAPbI3 was highly reproducible.展开更多
In recent years,solution-processible semiconductors with perovskite or perovskite-inspired structures have been extensively investigated for optoelectronic applications.In particular,silver-bismuth-halides have been i...In recent years,solution-processible semiconductors with perovskite or perovskite-inspired structures have been extensively investigated for optoelectronic applications.In particular,silver-bismuth-halides have been identified as especially promising because of their bulk properties and lack of heavily toxic elements.This study investigates the potential of Ag2BiI5 for near-infrared(NIR)-blind visible light photodetection,which is critical to emerging applications(e.g.,wearable optoelectronics and the Internet of Things).Self-powered photodetectors were realized and provided a near-constant≈100 mA W−1 responsivity through the visible,a NIR rejection ratio of>250,a long-wavelength responsivity onset matching standard colorimetric functions,and a linear photoresponse of>5 orders of magnitude.The optoelectronic characterization of Ag2BiI5 photodetectors additionally revealed consistency with one-center models and the role of the carrier collection distance in self-powered mode.This study provides a positive outlook of Ag2BiI5 toward emerging applications on low-cost and low-power NIR-blind visible light photodetector.展开更多
The vast majority of high-performance perovskite solar cells(PSCs) are based on a formamidinium lead iodide(FAPbI_(3))-dominant composition. Nevertheless, the FA-based perovskite films suffer from undesirable phase tr...The vast majority of high-performance perovskite solar cells(PSCs) are based on a formamidinium lead iodide(FAPbI_(3))-dominant composition. Nevertheless, the FA-based perovskite films suffer from undesirable phase transition and defects-induced non-ideal interfacial recombination, which significantly induces energy loss and hinders the improvement of device performance. Herein, we employed 4-fluorophenylmethylammonium iodide(F-PMAI) to modulate surface structure and energy level alignment of the FA-based perovskite films. The superior optoelectronic films were obtained with reduced trap density, pure α-phase FAPbI_(3) and favorable energy band bending. The lifetime of photogenerated charge carriers increased from 489.3 ns to 1010.6 ns, and a more “p-type” perovskite film was obtained by the post-treatment with F-PMAI. Following this strategy, we demonstrated an improved power conversion efficiency of 22.59% for the FA-based PSCs with an open-circuit voltage loss of 399 m V.展开更多
The photovoltaic performance of perovskite sloar cells(PSCs)is strongly dependent on the crystallinity,morphorlogy and defects of perovskite films.In the present work,a novel strategy was developed to fabricate the hi...The photovoltaic performance of perovskite sloar cells(PSCs)is strongly dependent on the crystallinity,morphorlogy and defects of perovskite films.In the present work,a novel strategy was developed to fabricate the high quality CsPbI3 inorganic perovskite by tuning the growth dynamics of CsPbI3 by pretreatment of fresh CsPbI3 films with phenylethylamine iodide(PEAI).The PEAI can mediate the phase transformation from 1D(DMAPbI3)(DMA:dimethylammonium)to 3D CsPbI3 all-inorganic perovskite films via the PEA2CsPb2I7 of 2D perovskite intermediate phase,resulting in highly crystalline CsPbI3 perovskite films with remarkably enlarged grains and reduced defects.The as-achieved highly crystalline CsPbI3 inorganic perovskite not only exhibited improved phase stability but also significant reduced defects.The perovskite solar cells based on these CsPbI3 thin films exhibited a champion efficiency of 17.08%,much higher than those prepared through posttreatment or direct addition of PEAI into CsPbI3 precursor solution.This work not only developed an effective strategy to prepare high crystalline CsPbI3 film and highly efficient CsPbI3-based all-inorganic PSCs,but also unraveled the mediation mechanism of CsPbI3by pre-treatment of PEAI,shedding light for further development of high perfomance perovskite-based optoelectronics.展开更多
Commercial application of the dye-sensitized solar cells（DSCs） depends on great improvement of the power conversion efficiency and reduction of the fabrication cost. Generally, developing low cost counter electrode ...Commercial application of the dye-sensitized solar cells（DSCs） depends on great improvement of the power conversion efficiency and reduction of the fabrication cost. Generally, developing low cost counter electrode catalysts to replace the expensive Pt counter electrode is a feasible path to reduce the production cost of DSCs. In this review article, we summarize the recent progress on the transition metal compound based counter electrode catalysts containing carbides, nitrides, oxides, sulfides, phosphide, selenides, borides, silicide, and telluride toward the regeneration of the traditional iodide redox couple.Moreover, the benefits and drawbacks of each kind of CE catalyst are discussed and the research directions to design new counter electrode catalysts in future research are also proposed.展开更多
Energy conversion efficiency of the dye-sensitized solar cell is improved from 3.5% to 4.5% by adding a small amount of CuI into an ionic liquid electrolyte. It is found that other copper-I salts, for example, CuBr, h...Energy conversion efficiency of the dye-sensitized solar cell is improved from 3.5% to 4.5% by adding a small amount of CuI into an ionic liquid electrolyte. It is found that other copper-I salts, for example, CuBr, have the same effect for the dye-sensitized solar cell. Experimental results show that no Cu^2＋ ions exist in this electrolyte. It is suggested that this improvement is caused by the adsorption of Cu^＋ onto the TiO2 porous film.展开更多
SiO2 nanoparticles were used to regulate the crystallizing process of lead halide perovskite films prepared by the sequential deposition method,which was used in the low-temperature-processed,carbon-electrode-basing,h...SiO2 nanoparticles were used to regulate the crystallizing process of lead halide perovskite films prepared by the sequential deposition method,which was used in the low-temperature-processed,carbon-electrode-basing,hole-conductor-free planar perovskite solar cells.It was observed that,after adding small amount of SiO2 precursor(1 vol%)into the lead iodide solution,performance parameters of open-circuit voltage,short-circuit current and fill factor were all upgraded,which helped to increase the power conversion efficiency(reverse scan)from 11.44(±1.83)%(optimized at 12.42%)to 14.01(±2.14)%(optimized at 15.28%,AM 1.5G,100 mW/cm^2).Transient photocurrent decay curve measurements showed that,after the incorporation of SiO2 nanoparticles,charge extraction was accelerated,while transient photovoltage decay and dark current curve tests both showed that recombination was retarded.The improvement is due to the improved crystallinity of the perovskite film.X-ray diffraction and scanning electron microscopy studies observed that,with incorporation of amorphous SiO2 nanoparticles,smaller crystallites were obtained in lead iodide films,while larger crystallites were achieved in the final perovskite film.This study implies that amorphous SiO2 nanoparticles could regulate the coarsening process of the perovskite film,which provides an effective method in obtaining high quality perovskite film.展开更多
Defect levels in semiconductor band gaps play a crucial role in functionalized semiconductors for practical applications in optoelectronics;however,first-principle defect calculations based on exchange-correlation fun...Defect levels in semiconductor band gaps play a crucial role in functionalized semiconductors for practical applications in optoelectronics;however,first-principle defect calculations based on exchange-correlation functionals,such as local density approximation,grand gradient approximation(GGA),and hybrid functionals,either underestimate band gaps or misplace defect levels.In this study,we revisited iodine defects in CH_(3)NH_(3)PbI_(3) by combining the accuracy of total energy calculations of GGA and single-electron level calculation of the GW method.The combined approach predicted neutral Im_(i) to be unstable and the transition level of Im_(i)(+1/-1)to be close to the valence band maximum.Therefore,Im_(i) may not be as detrimental as previously reported.Moreover,Vm I may be unstable in the-1 charged state but could still be detrimental owing to the deep transition level of Vm I(+1/0).These results could facilitate the further understanding of the intrinsic point defect and defect passivation observed in CH_(3)NH_(3)PbI_(3).展开更多
基金financially supported by the National Natural Science Foundation of China(U21A2078,22179042,and 12104170)the Natural Science Foundation of Fujian Province(2020J06021 and 2020J01064)Scientific Research Funds of Huaqiao University(23BS109)。
文摘Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other words,the PbI2 content in the precursor and as formed film will affect the efficiency and stability of the PSCs.With moderate residual PbI2,it passivates the bulk/surface defects of perovskite,reduces the interfacial recombination,promotes the perovskite stability,minimizes the device hysteresis,and so on.Deficient PbI2 residue will reduce the interfacial passivation effect and device performance.In addition to facilitating the non-radiative recombination,over PbI2 residue can also lead to electronic insulation in the grain boundary and deteriorate the device performance.However,the impact and regulation of PbI2 residue on the device performance and stability is still not fully understood.Herein,a comprehensive and detailed review is presented by discussing the PbI2 residue impact and its regulation strategies(i.e., elimination,facilitation and conversion of the residue PbI2) to manipulate the PbI2 content,distribution and forms.Finally,we also show future outlooks in this field,with an aim to help further the progression of high-efficiency and stable PSCs.
基金supported by Australian Research Council Discovery Project(DP190102252).
文摘The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material.In particular,nanocrystals(NCs)of inorganic perovskites have demonstrated excellent performance for light-emitting and display applications.However,the presence of surface defects on the NCs negatively impacts their performance in devices.Herein,we report a compatible facial post-treatment of CsPbI_(3) nanocrystals using guanidinium iodide(GuI).It is found that the GuI treatment effectively passivated the halide vacancy defects on the surface of the NCs while offering effective surface protection and exciton confinement thanks to the beneficial contribution of iodide and guanidinium cation.As a consequence,the film of treated CsPbI_(3) nanocrystals exhibited significantly enhanced luminescence and charge transport properties,leading to high-performance light-emitting diode with maximum external quantum efficiency of 13.8%with high brightness(peak luminance of 7039 cd m^(−2) and a peak current density of 10.8 cd A^(−1)).The EQE is over threefold higher than performance of untreated device(EQE:3.8%).The operational half-lifetime of the treated devices also was significantly improved with T50 of 20 min(at current density of 25 mA cm^(−2)),outperforming the untreated devices(T50~6 min).
基金the joint financial support from the National Natural Science Foundation of China (No. U1705256, 51972123, 21771066 and 61804058)the Cultivation Program for Postgraduate in Scientific Research Innovation Ability of Huaqiao University (No. 18014087027)。
文摘Perovskite solar cells have developed rapidly in the past decades.However,there are large amounts of ionic defects at the surface and grain boundaries of perovskte films which are detrimental to both the efficiency and stability of perovskite solar cells.Here,an organic halide salt pyridinium iodide(PyI) is used in cation-anion-mixed perovskite for surface defect passivation.Different from the treatment with Lewis base pyridine(Py) which can only bind to the under-coordinated Pb ions,zwitterion molecule PyI can not only fill negative charged iodine vacancies,but also interact with positive charged defects.Compared with Py treatment,PyI treatment results in smoother surface,less defect densities and nonradiative recombination in perovskite,leading to an improved VOC, negligible J-V hysteresis and stable performance of devices.As a result,the champion PyI-treated planar perovskite solar cell with a high VOC of 1.187 V achieves an efficiency of 21.42%,which is higher than 20.37% of Py-treated device,while the pristine device without any treatment gets an efficiency of 18.83% at the same experiment conditions.
基金Project supported by the Key Research and Development Program of China(Grant No.2020YFB1506400)the National Natural Science Foundation of China(Grant Nos.51922074,51673138,51820105003,and 22075194)+1 种基金the Tang Scholar,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Collaborative Innovation Center of Suzhou Nano Science and Technology.
文摘Formamidinium lead triiodide(FAPbI_(3))is a research hotspot in perovskite photovoltaics due to its broad light absorption and proper thermal stability.However,quite a few researches focused on the stability of the FAPbI_(3) perovskite precursor solutions.Besides,the most efficient FAPbI_(3) layers are prepared by the spin-coating method,which is limited to the size of the device.Herein,the stability of FAPbI_(3) perovskite solution with methylammonium chloride(MACl)or cesium chloride(CsCl)additive is studied for preparing perovskite film through an upscalable blade-coating method.Each additive works well for achieving a high-quality FAPbI_(3) film,resulting in efficient carbon electrode perovskite solar cells(pero-SCs)in the ambient condition.However,the perovskite solution with MACl additive shows poor aging stability that noα-FAPbI_(3) phase is observed when the solution is aged over one week.While the perovskite solution with CsCl additive shows promising aging stability that it still forms high-quality pureα-FAPbI_(3) perovskite film even the solution is aged over one month.During the solution aging process,the MACl could be decomposed into methylamine which will form some unfavored intermediated phase inducingδ-phase FAPbI_(3).Whereas,replacing MACl with CsCl could effectively solve this issue.Our founding shows that there is a great need to develop a non-MACl FAPbI_(3) perovskite precursor solution for cost-effective preparation of pero-SCs.
基金Project supported by the Science Challenge Project(Grant No.TZ2016004)。
文摘Study of two-dimensional(2D)magnetic materials is important for both fundamental research and application.Here we report molecular beam epitaxy growth of iodides,candidates for exhibiting 2D magnetism.Decomposition of CrI_(3)is utilized to produce stable gaseous I_(2)flux.Growth of MnI_(2),GdI_(3),and CrI_(2)down to monolayer is successful achieved by co-depositing I2 and corresponding metal atoms.The thin films of the three materials are characterized by scanning tunneling microscope and found to be insulators with bandgaps of 4.4 e V,0.6 e V,and 3.0 e V,respectively.The film growth paves the way for further study of magnetic properties at the 2 D limit.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61377065 and 61574064)the Science and Technology Planning Project of Guangdong Province,China(Grant Nos.2013CB040402009 and 2015B010132009)the Science and Technology Project of Guangzhou City,China(Grant No.2014J4100056)
文摘The morphology of the copper iodide （CuI） film as an inorganic p-type material has an important influence on enhancing the performance of polymer solar cells （PSCs）. A self-assembled monolayer of 3-aminopropanoic acid （C3-SAM） was used on the surface of indium tin oxide （ITO） before depositing the CuI films. Consequently, a well-distributed and smooth CuI film was formed with pinhole free and complete surface coverage. The root mean square of the corresponding CuI film was reduced from 3.63 nm for ITO/CuI to 0.77 nm. As a result, the average power conversion efficiency （PCE） of PSCs with the device structure of ITO/C3-SAM/CuI/P3HT：PC61BM/ZnO/Al increased significantly from 2.55% （best 2.66%） to 3.04% （best 3.20%） after C3-SAM treatment. This work provides an effective strategy to control the morphology of CuI films through interracial modification and promotes its application in efficient PSCs.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11974076 and 61804030)the Key Project of Natural Science Foundation of Fujian Province(Grant No.2021J02012)。
文摘Two-dimensional(2D)topological insulators present a special phase of matter manifesting unique electronic properties.Till now,many monolayer binary compounds of Sb element,mainly with a honeycomb lattice,have been reported as 2D topological insulators.However,research of the topological insulating properties of the monolayer Sb compounds with square lattice is still lacking.Here,by means of the first-principles calculations,a monolayer SbI with square lattice is proposed to exhibit the tunable topological properties by applying strain.At different levels of the strain,the monolayer SbI shows two different structural phases:buckled square structure and buckled rectangular structure,exhibiting attracting topological properties.We find that in the buckled rectangular phase,when the strain is greater than 3.78%,the system experiences a topological phase transition from a nontrivial topological insulator to a trivial insulator,and the structure at the transition point actually is a Dirac semimetal possessing two type-ⅠDirac points.In addition,the system can achieve the maximum global energy gap of 72.5 meV in the topological insulator phase,implying its promising application at room temperature.This study extends the scope of 2D topological physics and provides a platform for exploring the low-dissipation quantum electronics devices.
文摘Conversion of methanol(MeOH) to 2,2,3-trimethylbutane(triptane) over zinc iodide(ZnI_2)catalyst was investigated in a closed batch reactor.Optimum operating parameters were searched and catalyst deactivation and regeneration behaviors were discussed.The fresh,spent and regenerated catalysts were characterized by XRD,TG and XRF measurements to elucidate the related mechanism.The experimental results showed that the triptane yield reached up to 12.2% under the process conditions,including a reaction temperature of 200℃,an initial pressure of 0.35 MPa,a reaction time of 2 h,and a Me OH to ZnI_2 molar ratio of 2.The catalyst was gradually deactivated after several run cycles.A small amount of iodine was lost and a certain amount of ZnO was formed on the deactivated ZnI_2 catalyst.Deactivation of the catalyst could be attributed to the reduction of ZnI_2 amount,resulted from iodine loss and formation of Zn O.It was firstly pointed out from our work that the deactivated catalyst could be well regenerated by the hydrogen iodide(HI) and the tert-butanol compensation method,wherein the latter was added as an initiator into the reaction system.The activity recovery of the deactivated(spent) catalyst might be related to the reformation of ZnI_2 and acceleration of the initiation step of this reaction.
基金funded partly by the National Natural Science Foundation of China(Grant No.51950410581)the Shanghai Pujiang Program+2 种基金the Open Fund of Zhejiang Tsinghua Institute of Flexible Electronics Technologyfunding from the National Natural Science Foundation of China(Grant No.21604053)funding from the ECNU Multifunctional Platform for Innovation(003,006).
文摘Previous reports of formamidinium/methylamine(FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example,through the inclusion of bromine and surface passivation.In this paper,we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase.Through low-temperature aging growth(LTAG)of a freshly deposited perovskite film,α-phase perovskites can be seeded in the intermediate phase and,at the same time,prevent beta-phase perovskite to nucleate.After postannealing,large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained,thereby eliminating the need of additional surface passivation step.Our pristine LTAG-treated solar cells could provide PCEs of greater than 22%without elaborate use of bromine or an additional passivation layer.More importantly,when using this LTAG process,the growth of the pure alpha-phase FAMAPbI3 was highly reproducible.
基金financial support from the National Natural Science Foundation of China (61750110517 and 61805166)the Jiangsu Province Natural Science Foundation (BK20170345)+3 种基金supported by the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the 111 Projectthe Joint International Research Laboratory of Carbon-Based Functional Materials and Devices
文摘In recent years,solution-processible semiconductors with perovskite or perovskite-inspired structures have been extensively investigated for optoelectronic applications.In particular,silver-bismuth-halides have been identified as especially promising because of their bulk properties and lack of heavily toxic elements.This study investigates the potential of Ag2BiI5 for near-infrared(NIR)-blind visible light photodetection,which is critical to emerging applications(e.g.,wearable optoelectronics and the Internet of Things).Self-powered photodetectors were realized and provided a near-constant≈100 mA W−1 responsivity through the visible,a NIR rejection ratio of>250,a long-wavelength responsivity onset matching standard colorimetric functions,and a linear photoresponse of>5 orders of magnitude.The optoelectronic characterization of Ag2BiI5 photodetectors additionally revealed consistency with one-center models and the role of the carrier collection distance in self-powered mode.This study provides a positive outlook of Ag2BiI5 toward emerging applications on low-cost and low-power NIR-blind visible light photodetector.
基金funded by the National Natural Science Foundation of China(62004165)the China Postdoctoral Science Foundation(2020M670036)+2 种基金the Natural Science Foundation of Shaanxi Province,China(2020JQ195)the Joint Research Funds of Department of Science&Technology of Shaanxi Province and Northwestern Polytechnical University(2020GXLH-Z-007,2020GXLH-Z-025)the Fundamental Research Funds for the Central Universities。
文摘The vast majority of high-performance perovskite solar cells(PSCs) are based on a formamidinium lead iodide(FAPbI_(3))-dominant composition. Nevertheless, the FA-based perovskite films suffer from undesirable phase transition and defects-induced non-ideal interfacial recombination, which significantly induces energy loss and hinders the improvement of device performance. Herein, we employed 4-fluorophenylmethylammonium iodide(F-PMAI) to modulate surface structure and energy level alignment of the FA-based perovskite films. The superior optoelectronic films were obtained with reduced trap density, pure α-phase FAPbI_(3) and favorable energy band bending. The lifetime of photogenerated charge carriers increased from 489.3 ns to 1010.6 ns, and a more “p-type” perovskite film was obtained by the post-treatment with F-PMAI. Following this strategy, we demonstrated an improved power conversion efficiency of 22.59% for the FA-based PSCs with an open-circuit voltage loss of 399 m V.
基金supported by the National Natural Science Foundation of China(No.51602106)。
文摘The photovoltaic performance of perovskite sloar cells(PSCs)is strongly dependent on the crystallinity,morphorlogy and defects of perovskite films.In the present work,a novel strategy was developed to fabricate the high quality CsPbI3 inorganic perovskite by tuning the growth dynamics of CsPbI3 by pretreatment of fresh CsPbI3 films with phenylethylamine iodide(PEAI).The PEAI can mediate the phase transformation from 1D(DMAPbI3)(DMA:dimethylammonium)to 3D CsPbI3 all-inorganic perovskite films via the PEA2CsPb2I7 of 2D perovskite intermediate phase,resulting in highly crystalline CsPbI3 perovskite films with remarkably enlarged grains and reduced defects.The as-achieved highly crystalline CsPbI3 inorganic perovskite not only exhibited improved phase stability but also significant reduced defects.The perovskite solar cells based on these CsPbI3 thin films exhibited a champion efficiency of 17.08%,much higher than those prepared through posttreatment or direct addition of PEAI into CsPbI3 precursor solution.This work not only developed an effective strategy to prepare high crystalline CsPbI3 film and highly efficient CsPbI3-based all-inorganic PSCs,but also unraveled the mediation mechanism of CsPbI3by pre-treatment of PEAI,shedding light for further development of high perfomance perovskite-based optoelectronics.
基金supported by National Natural Science Foundation of China(21303039)Natural Science Foundation of Hebei Province(B2015205163,B2013205171)+1 种基金Support Program for Hundred Excellent Innovation Talents from the Universities of Hebei Province,(BR2-220)supported by Science Foundation of Hebei Normal University(L2016J02)
文摘Commercial application of the dye-sensitized solar cells（DSCs） depends on great improvement of the power conversion efficiency and reduction of the fabrication cost. Generally, developing low cost counter electrode catalysts to replace the expensive Pt counter electrode is a feasible path to reduce the production cost of DSCs. In this review article, we summarize the recent progress on the transition metal compound based counter electrode catalysts containing carbides, nitrides, oxides, sulfides, phosphide, selenides, borides, silicide, and telluride toward the regeneration of the traditional iodide redox couple.Moreover, the benefits and drawbacks of each kind of CE catalyst are discussed and the research directions to design new counter electrode catalysts in future research are also proposed.
基金Supported by the National Natural Science Foundation of China under Grant No 20673141, the National Basic Research Programme of China under Grant No 2006CB202606, the National High Technology Research and Development Programme of China under Grant No 2006AA03Z341, and the 100-Talents Project of Chinese Academy of Sciences.
文摘Energy conversion efficiency of the dye-sensitized solar cell is improved from 3.5% to 4.5% by adding a small amount of CuI into an ionic liquid electrolyte. It is found that other copper-I salts, for example, CuBr, have the same effect for the dye-sensitized solar cell. Experimental results show that no Cu^2＋ ions exist in this electrolyte. It is suggested that this improvement is caused by the adsorption of Cu^＋ onto the TiO2 porous film.
基金Project supported by the Fundamental Research Funds for the Central South University,China(Grant No.2019zzts426)the National Natural Science Foundation of China(Grant Nos.61172047,61774170,and 51673218)+1 种基金the Scientific and Technological Project of Hunan Provincial Development and Reform Commission,China,the National Science Foundation,USA(Grant Nos.CBET-1437656 and DMR-1903962)the Innovation-Driven Project of Central South University(Grant No.2020CX006)。
文摘SiO2 nanoparticles were used to regulate the crystallizing process of lead halide perovskite films prepared by the sequential deposition method,which was used in the low-temperature-processed,carbon-electrode-basing,hole-conductor-free planar perovskite solar cells.It was observed that,after adding small amount of SiO2 precursor(1 vol%)into the lead iodide solution,performance parameters of open-circuit voltage,short-circuit current and fill factor were all upgraded,which helped to increase the power conversion efficiency(reverse scan)from 11.44(±1.83)%(optimized at 12.42%)to 14.01(±2.14)%(optimized at 15.28%,AM 1.5G,100 mW/cm^2).Transient photocurrent decay curve measurements showed that,after the incorporation of SiO2 nanoparticles,charge extraction was accelerated,while transient photovoltage decay and dark current curve tests both showed that recombination was retarded.The improvement is due to the improved crystallinity of the perovskite film.X-ray diffraction and scanning electron microscopy studies observed that,with incorporation of amorphous SiO2 nanoparticles,smaller crystallites were obtained in lead iodide films,while larger crystallites were achieved in the final perovskite film.This study implies that amorphous SiO2 nanoparticles could regulate the coarsening process of the perovskite film,which provides an effective method in obtaining high quality perovskite film.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11974257)the Distinguished Young Talent Funding of Jiangsu Province, China (Grant No. BK20200003)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Defect levels in semiconductor band gaps play a crucial role in functionalized semiconductors for practical applications in optoelectronics;however,first-principle defect calculations based on exchange-correlation functionals,such as local density approximation,grand gradient approximation(GGA),and hybrid functionals,either underestimate band gaps or misplace defect levels.In this study,we revisited iodine defects in CH_(3)NH_(3)PbI_(3) by combining the accuracy of total energy calculations of GGA and single-electron level calculation of the GW method.The combined approach predicted neutral Im_(i) to be unstable and the transition level of Im_(i)(+1/-1)to be close to the valence band maximum.Therefore,Im_(i) may not be as detrimental as previously reported.Moreover,Vm I may be unstable in the-1 charged state but could still be detrimental owing to the deep transition level of Vm I(+1/0).These results could facilitate the further understanding of the intrinsic point defect and defect passivation observed in CH_(3)NH_(3)PbI_(3).
